1914.] 



REITHKODONTOMYS MEGALOTIS GROUP. 



29 



Intergradation with longicaudus is perfectly shown by a large 

 series from the Mojave Desert in southern CaHfornia. In color these 

 specimens are intermediate between the two races, but rather nearer 

 to megalotis, while in skull characters they most resemble longicaudus. 

 Some individuals in the series much resemble nigrescens^ but are 

 generally more suffused with buff. A series from the south fork of 

 Kern Eiver, Cal., are nearly typical megalotis but slightly browner. 



In New Mexico the typical form occurs only in the extreme south- 

 ern part, near the Mexican boundary, a gradual increase in size of 

 skuU being observed as we proceed northward toward the range of 

 aztecus. Southward over the Mexican table-land there is no percep- 

 tible change in color as far as Zacatecas. Specimens from north- 

 western Durango, described by Allen under the name " sestinensis,^^ 

 do not differ appreciably from the typical form. 



Specimens examined. — Total number, 415, from the following 

 locahties : 



Idaho: American Falls, 2; Swan Lake, 1. 



California: Amedee, 2; Argus Mountains, 1; Barstow, 12; Bishop Creek, 1; 

 Cartago, Owens Lake, 10; Colorado River (opposite Parker, Ariz.), 4; Emi- 

 grant Spring, 1; Fort Yuma, 1; Furnace Creek, Death Valley, 5; Grapevine 

 Spring, 4; Keeler, 4; Lone Pine, 30; Long Valley (Lassen County), 4; Mojave, 

 3;^ Olanche, Owens Lake, 22; Owens Valley, 8; Onyx, south fork of Kern 

 River, 19;^ Panamint Mountains, 7; Panamint Valley, 2; Pilot Knob, 8; 

 Resting Spring, 3; Saratoga Spring, 3; Shepherd Canon, Argus Mountains, 

 1; Tehachapi, 20;i Twelve Mile Spring, Inyo County, 1; Victorville, 1.^ 2 



Nevada: Ash Meadows, 30; Carson Sink, 1; Fallon, 5; Gardnerville, 1; Grape- 

 vine Mountains, 2; Oasis Valley, 16; Pahranagat Valley, 4; Pahrump Valley, 

 11; Panaca, 1; Pine Forest Mountains, 7;^ Quinn River Crossing, 20;^ St. 

 Thomas, 1; Smoky Creek, 1; Vegas Valley, 5; Verdi, 3; Virgin Valley, 1.^ 



Arizona: Colorado River at Monument No. 204, Mexican boundary, 27; Fair- 

 bank, 2; Grand Canyon (Indian Gardens), 2; Lee's ferry, 1; Pai'ker, 5; St. 

 Johns, 2; Winslow, 17; Zuni River, 1. 



New Mexico: Animas Valley, 1; Deming, 3; Dry Creek, Socorro County, 3; Fair- 

 view, 1; Gallo Canyon, 35 miles southeast of Corona, 1; Gila, Grant County, 1; 

 Glen wood, 1; Jicarilla Mountains, 1; Kingston, 2; Las Cruces, 3; Las Palo- 

 mas, 5; Mesa Jumanes, 2; Monument No. 15, Mexican boundary, 1; Monu- 

 ment No. 40, Mexican boundary, 3; Organ Mountains, 3; Pleasanton, 1; 

 Redrock, Grant County, 1; Roswell, 1; San Andreas Mountains, 2; San 

 Mateo Mountains, Socorro County, 2; Silver City, 3; Tularosa, 5. 



Texas: Alpine, 1; 25 miles west of Fort Stockton, 1; Franklin Mountains, 1; 

 Guadalupe Mountains, 1; Pecos City, 1. 



Lower California: Gardners Lagoon, 1; Seven Wells, 2, 



Sonora: Cienega Well, 30 miles south of Monument No. 204, Mexican boundary, 1. 

 Chihuahua: Casas. Grandes, 4; Chihuahua, 2. 

 Coahuila: Saltillo, 1; Sierra Guadalupe, 1. 

 Durango: Rio Sestin, 4.* 

 Zacatecas: Zacatecas, 2. 



1 Approaching longicaudus. 



2 Received from Jos. Grinnell. 



s Collection Mus. Vert. Zool., Univ. of Cal. 

 4 Collection Amer. Mus. Nat. Hist. 



